The Netwide Assembler (NASM) is an assembler and disassembler for the Intel x86 architecture. It can be used to write 16-bit, 32-bit (IA-32) and 64-bit (x86-64) programs. NASM is considered to be one of the most popular assemblers for Linux.NASM was originally written by Simon Tatham with assistance from Julian Hall and is currently maintained by a small team led by H. Peter Anvin. It is open-source software available under the terms of the simplified (2-clause) BSD license.